Background

Add a constant value to numbers matched with a regular expression, using vim (gvim).

Problem

The following regular expression will match width="32":

/width="\([0-9]\{2\}\)"

Question

How do you replace the numeric value of the width attribute with the results from a mathematical expression that uses the attribute's value? For example, I would like to perform the following global replacement:

:%s/width="\([0-9]\{2\}\)"/width="\1+10"/g

That would produce width="42" for width="32" and width="105" for width="95".